Process for the preparation of an expanded plastisol composition



I PROCESS FOR THE PREPARATION OF AN EXPANDED PLASTISOL COMPOSITIONWillard E. Catlin, Woodstown, and Mack F. Fuller, Woodbury, N.J.,.assignors to. E]. du Pont de Nemours and Company, Wilmington, Del., acorporation of Delaware No Drawing. Application May 24, 1954 Serial No.432,055

8 Claims. (Cl. 260-25) This invention relates to the manufacture ofcellular plastic material and in particular to an improved process forsuch manufacture, and the products of such process.

In U.S. patent application 343,265, filed March 18, 1953, and having acommon assignee with the instant application, there is disclosed a novelprocess for the preparation of cellular polyvinyl chloride with achemical blowing agent. This novel process differs generally from priorart processes in that it involves heating a plastisol composition atatmospheric pressure and at temperatures which permit decomposition ofthe blowing agent and consequentv foaming of the composition beforegelation of the plastisol occurs. The composition isthen heated furtherto flux the resin with the plasticizer. Such a process obviates the-needfor expensive high-pressure equipment hitherto required for obtainingmaterials having low densities and. thick sections. In addition, thisprocess permits much wider choice of compounding ingredients than doprocessesof the prior, art.

We now have found that wecan greatly. improve the product obtained withthis atmospheric pressure foaming process by the addition of certain.hydrocarbon oil=soluble additives to the plastisol before heating. Thesurfaceactive materials which we have found most effective are thealkali. metal and alkaline earth metal salts of sulfonic acids. Weprefer to use the alkaline earth metal salts of the alkaryl sulfonicacids. Especially preferred are the alkaline earth metal salts ofalkaryl monosulfonic acids. Mixtures, containing salts of alkarylsulfonic acids, which have been obtained asby-products during thesulfonation of petroleum stocks in the manufacture of refined paraffinicoils may be used in this process. Alternatively, these additives may besynthesized directly by. the alkylation of benzene and subsequentsulfonation of the resulting alkyl benzene. We prefer to use compoundsprepared synthetically by monosulfonation of the products resulting fromdialkylation of benzene with C -olefins.

Though the use of such additives is not critical to the successfulpractice of the basic process as disclosed in the earlier application,vtheir inclusion in the plastisol makes possible a consistently finersponge product having more uniform cell structure and lower density.Furthermore, the additives affect the blowing process in a mannerpermitting a. much wider choice of compounding ingredients.

The invention will be better understood from a consideration of thefollowing examples, in which all parts are by weight:

Example 1 A plastisol was prepared by mixing together the followingingredients:

2,904,522 Patented Sept. 15, 1959 Parts Geon 121 1 Ohopex Q-l0 102Methyl pentachlorostearate 48 Dibasic lead phosphite 5 N,N'-dinitroso,N,N-dimethyl terephthalamide 8-.4 Primol-D 3 3;.6

Dispersion-grade polyv'nyl chloride manufactured by the B. F. GoodrichChemical Co. A Ocyl fatty-phthalic acid esters, manufactured by Ohiopexnc.

A white parafiim'c hydrocarbon oil, manufactured by Esso Standard OilCompany.

The plastisol was poured intoan aluminum pan having an inner diameterof- 3 /2 inches, a depth of 2 inches, and a wall thickness of 0.03 inch.The plastisol was poured into the pan to a depth of inch, then heated inan oven having an air temperature of 100 C. until foaming was complete,as indicated by a change in color of the plastisol from. yellow to:white. The plastisol was then further heated in an oven having an airtemperature of C. for 45 minutes.

The product was a white sponge, free from objectionable odor; It had anopen (sometimes called continu ous) cell structure; a density of 8.3lbs. per cubic'foot; a volume 10 /2 times that ofthe originalwplastisol;and a rough uneven surface.

Example 2 The procedure of Example 1 was repeated except that 3.5 partsof barium petroleum sulfonate (a mixture of barium di-o-dodecyl benzenemonosulfonate and barium di-p-dodecylbenzene monosulfonate (30% activeingredient having mol. wt. 991 A.S.T.M. base No; 0.5), manufactured byBryton Chemical Co. was added to the plastisol. The product was a whitesponge, free from objectionable odor. It had a medium-fine, open cellstructure, a density of 6.7 lbs. per cubic foot, and a volume 12% timesthat of the original plastisol.

Example 3 Dispersion-grade polyvinyl chloride manufactured by the B. F.Goodrich Chemica=l Co.

A monomeric epoxy fatty 301d ester, manufactured by Rohrn- 8a Haas Co. AOci'yI fatty phth alic acid esters, manufactured by Ohiopex nc. e

A mixture of barium di-o-dodecyl benzene monosulfonate and bariumdisp-dodecyl benzene monosulfonate (30% active ingredient having mol.wt. 991, A.S.T.M. base N0. 05); manufactured by Bryton Chemical Co.

A white paratfinic hydrocarbon oil, manufactured by Esso- Sbandard. 011Company.

The plastisol was treated in exactly the same manner as that ofExample 1. The product was a white sponge, free from objectionable odor.It had a'fine, uniform opencell structure, a density of 7.25 lbs. percubic foot, and a volume 11.75 times that of the original plastisol.

Example 4 The procedure of Example 3 was repeated except that the bariumpetroleum sulfonate was omitted from the plastisol. The product was arough white sponge, free from objectionable odor. It had a very coarse,uneven cell structure and a volume of 8 times that of the originalplastisol.

Example 5 A plastisol was prepared by mixing together the followingingredients:

Parts Dispersion-grade polyvinyl chloride manufactured by the B. F.Goodrich Chemical Co.

An epoxy polyester (average mol. wt. 1000, specific gravity (25 C./15C.) 0.990, viscosity (100%, 25 C.) 2-3 poises, refractive index (Nn25)1.472, freezing point 5 C.), manufactured by Rohm & Haas Co. inaccordance with U.S. Patent No. 2,485,160, issued October 18, 1949.

Chlorinated paraflin containing 40% combined chlorine by weight,manufactured by Diamond Alkali Co.

11 mixture of barium di-o-dodecyl benzene monosulfonate and bariumdi-p-dodecyl benzene monosulfonate (30% active ingredient havln mol. wt.991, A.S.T.M. base No. 0.5), manufactured by ryton Chemical Co.

The plastisol was treated in exactly the same manner as that ofExample 1. The product was a white sponge, free from objectionable odor.It had a density of 7 lbs. per cubic foot and a volume 12 times that ofthe original plastisol.

Example 6 The procedure of Example was repeated except that the bariumpetroleum sulfonate was omitted from the plastisol. The product was awhite sponge, free from objectionable odor. It was badly collapsed andhad a very course and uneven cell structure. Expansion was very slight.

Example 7 A plastisol was prepared by mixing together the followingingredients:

Dispersion-grade polyvinyl chloride manufactured by the B. F. GoodrichChemical Co. An epoxy polyester (average mol. wt. 1000, specific grav-1ty (25 C./15 C.) 0.990, viscosity (100%, 25 C.) poises, refractiveindex (Nn25) 1.472, freezing point 05 0.), manufactured by Rohm & HaasCo. in accordance with U.S. Patent No. 2,480,160. issued October 18,1949.

Octyl fatty-phthalic acid esters, manufactured by Ohio- Apex Inc.

A mixture of barium di-o-dodecyl benzene monosulfonate and bariumdi-p-dodecyl benzene monosulfonate (30% active ingredient having mol.wt. 991, A.S.T.M. base N0. O.5), manufactured by Bryton Chemical Co.

A white paraffinic hydrocarbon oil, manufactured by Esso Standard OilCompany.

Example 8 A plastisol was prepared by mixing together the followingingredients:

Parts Geon 121 1 Paraplex G-60 2 50 Di-Z-ethyhexyl phthalate 50 Dibasiclead phosphite 5 Barium petroleum sulfonate 3.6 N,N'-dim'troso,N,N'-dimethyl terephthalamide 7 Primol-D 4 3 Dispersion-grade polyvinylchloride manufactured by the B. F. Goodrich Chemical Co.

An epoxy polyester (average mol. wt. 1000, ity (25 C./15 C.) 0.990,viscosity (100%, 25 o 2- poises, refractive index (Nn25) 1.472, freezingpoint 0 Cg, manufactured by Rohm & Haas Co. in accordance with U. PatentNo. 2,485,160, issued October 18, 1949.

A mixture of barium di-o-dodecyl benzene monosulfonate and bariumdip-dodecyl benzene monosulfonate (30% active ingredient having mol. wt.991, A.S.T.M. base No. 0.5), manufactured by Bryton Chemical Co.

=A white paraffinic hydrocarbon oil, manufactured by Esso Standard OilCompany.

The plastisol was treated in exactly the same manner as that ofExample 1. The product was a white sponge, free from objectionable odor.It had a very fine open cell structure, a density of 7.5 lbs. per cubicfoot, and a volume 11.5 times that of the original plastisol.

Example 9 A plastisol was prepared by mixing together the follow-Primo-D 6 3 Dispersion-grade polyvinyl chloride manufactured by the B.F. Goodrich Chemical Co.

An epoxy polyester (average mol. wt. 1000, specific gravity (25 C./15C.) 0.990, viscosity (100%, 25 C. 2-3 poises, refractive index (Nn25)1.472, freezing point 0 5 C.), manufactured by Rohm & Haas Co. inaccordance with U.S. Patent No. 2,485,160, issued October 18, 1949.

A ocltyl fatty-phthalic acid esters, manufactured by Ohiopex nc.

A partially hydrogenated, alkylated aromatic hydrocarbon oil,manufactured by Monsanto Chemical Co.

A mixture of barium di-o-dodecyl benzene monosulfonate and bariumdi-p-dodecyl benzene monosulfonate (30% active ingredient having mol.wt. 991, A.S.T.M. base No. 0.5), manufactured by Bryton Chemical Co.

A white parafiinic hydrocarbon oil, manufactured by Esso Standard OilCompany.

The plastisol was treated in exactly the same manner as that ofExample 1. The product was a white sponge, free from objectionable odor.It had an open cell structure, a density of 7 lbs. per cubic foot, and avolume 12 times that of the original plastisol.

Example 10 A plastisol was prepared by mixing together the followingingredients:

Dispersion-grade polyvinyl chloride manufactured by the B. F. GoodrichChemical Co.

2 An epoxy polyester (average mol. wt. approx. 1000, specific gravity(25 C./15 C.) 0.993, freezing point 05 C.), manufactured by Rohm & HaasCo.

Chlorinated parafiin containing 40% combined chlorine by weight,manufactured by Diamond Alkali Co.

-A mixture of non-toxic soaps, manufactured by Witco Chemical Co.

A mixture of barium di-o-dodecyl benzene monosulfonate and bariumdi-p-dodecyl benzene monosulfonate (30% active ingredient having mol.wt. 991, A.S.T.M. base No. 0.5), manufactured by Bryton Chemical Co.

A white parafiinic hydrocarbon oil, manufactured by Esso Standard OilCompany,

Example 1 1 a a plastisol was prepared by mixing together the followingingredients: 1

r Exon 654i w w o iqthylheiyl' d llfi lwp osphate c 28 ChIoroWaX 3 16 gDi- 2'-ethylhe'xyl phthfalate .r; 16 W'tco stabi e" #90 p 1 i3 perm ulfdate 3.

N,'N'-di'nitros o-, N,N'-diiiiethyl terephthalamide 7 PrimO1 D 6 v l I 1nispcrsiomgraae Firestone Plastics Co .v v {An epoxy. polyester.(average ,mol. Ywt. approx. 1000', specific gravity (25 C./ C.) 0.993,freezing point 05 0.), manufactured by.Rohm&Haas,Co, g v I Chlorinatedparatfin containing 40% combined chlorine by weight, manufactured byDiamond AlkaliCo. mixture of non-toxic soaps, manufactured by Witco ele2 1 v r EA mixturef-barium-di-'o-dodecyl benzene monosulfonate and;barium di -p dodecyl bjenzenemonosulfonate (30% activeingredienbdiaving mol, wt. 991 A.S.T.M. base No.. 05), manufactured byBryton Chemical Co. 1 .SAmbite paraflinic, hydrocarbon oil, manufacturedby Esso Standard OilCompany.

polyvinyl chloride, manufactured by Example 12 A plasti sol was preparedby mixing together the following ingredients:

H Parts ,TG Tn 11 0 fP ara'plex G550 2 ,UP X Q-JOZF U Methyl'p'hfachlor'osta'rate c 24 Dibasic lead phosphite 5 Calcium petroleumsulfon'ate 3.6 N,N'- 1ffiiir6sb, N',N"-diiiiethylt eph'thalamide 7Priinol-D 3 Dispersion-g-rade polyvinyl chloride.manufactured by theB.lhGoqdricl Chemical Co.

.- A(n epor'gp poly'z'ter (average mol, wt. 1000, spe cificgrav- My 2515 .fpoises, refractive index (Nn25) 1.472. freezing point 05 .C.),

0.990, yiscosity... (10.07%, 20 C.) 2

manufactured by Rollin '& Haas Co. in accordance with U.S. Patent No.2,485,160, issued October..18,,1949. OcItyl fatty-phthalicacid esters,manufactured by Ohio- A ex no.

A mixture of calcium di-o-decyl.benzene moi o'sulf onate and, calciumdhmdodecyl benzene monosulfonate (30% active ingredient having moi. wt.884) manufactured by Bryto n m m 'A white paraflinic hydrocarbon oil,manufactured by Esso Standard Oil Company.

i' i licnt sponge, free from objectionable 'o'dor. It had a veryifine,open cell 'structm-e a density of 7.5 lbs. per 'cubic foot, "and avolume 11.5 times that of the original plastisol.

6 E'itarizple 13 together" the 01- I'oyififig ingredients:

Disprsi'on grade polyvinyl chloride manufactured by the B. F. GoodrichCh'emical Co p 4A polyadipateltspecificravity (25" C./1 5 C.) 1-2,--V.is'- cosit 25 C.) 2.7 3.25 poises), manufactured by the eneralElectrici lm, g an epoxy poiyesten'iavrag'e mol, w't. 1000, specificgrav: ity,v (25 L/1f 0.990,. viscosity 100%, 25 0.). 2-3 poises,refractive in x '(Nn25 1.472, freezingp'o'int 0'5 Cg, manufacturedbyRohm Haas Co. in accordance with U. Patent No. 2,485,160, issued October18, 1 949.

A mixture of ,,neutral sodium di-o-dodecyl benzene monosulfonate, andsodium 'di-p-dodecyl benzene monosulfonate (62.% active ingredienthaving mol. wt. 490), manufactured by IBryton Chemical Co .J Awhite.parafiinic hydrocarbon oil; manufacturedby Esso Standard Oil Company. g

The plastisol was treated in exactly the same manner as that of Example1.- The product was a white sponge, free from objectionable odo It had averyfine, open cell structure and a volume 14 times that of the originalplastisol.

Example 14 This sponge had a fissure through its center. 1

Example 15 A plasma was prepared by mixing together'the follow ingingredients:

. 'Dispersi'o'n gra.d'e,polyvinyl chloride manufactured by the B. F.Goodrich ChemicalCo. v I,

. A'n epoxy polyester ("average mol, wt. 1000, specific gravity (25C./15 C. 0.990, viscosity (100%, 25 C.) 2+3 poises, refractive in ex(Nn25) 1.472, freezing point 0 5 Cw), manufactured by Robin & Haas Co.in accordance with U.S. Patent No. 2,485,160, issued October 18, 1949.

A 'ocltyl fatty-phthalic acid esters, manufacturedby Ohiopex nc.

4 The barium salt of an alkaryl sulfonic acid, 'obtained'as a by-productin the sulfuric acid refining of petroleum stocks (58.5% activeingredients having mol. wt. 981 A.S.T.M. base No. 0), manufactured'by L.Sonneborn Sons, inc.

, A wliiteparaffinic hydrocarbon oil, manufactured by Esso Standard OilCompany.

The plastisol was treated in exactly the same manner as "that ofExample 1. The product was a 'white sponge,

free from objectionable'odor. It had anopen-cell -struc tuieaiid adeiisity or 715's. per cubic 'foot.

7 Example 16 A plastisol was prepared by. mixing together the follow ingingredientsz' p ,Geon 121 100 Paraplex G60 36 Ohopex Q-10 3 32Dispersion-grade polyvinyl chloride manufactured by the B. F. GoodrichChemical Co.

An epoxy polyester (average mol, wt. 1000, specific gravity (25 C./15C.) 0.990, viscosity (100%, 25 C.) 23 poises, refractive index (Nn25)1.472, freezing point 5 C.), manufactured by Rohm & Haas Co. inaccordance with U.S. Patent No. 2,485,160, issued October 18, 1949.

Octyl fatty-phthaiic acid esters, manufactured by Ohio- Apex Inc.

The calcium salt of an alkaryl sulfonic acid, obtained as a by-productin the sulfuric acid refining of petroleum stocks (58.5% activeingredients having mol. wt. 888, A.S.'I..M. base No. 0), manufactured byL. Sonneborn Sons, Inc.

A white paraffinic hydrocarbon oil, manufactured by Esso Standard OilCompany.

The plastisol was treated in exactly the same manner as that ofExample 1. The product was a white sponge, free from objectionable odor.It had a fine, open cell structure, a density of 7.7 lbs. per cubicfoot, and a volume 11.3 times that of the original plastisol.

' Example 17 A plastisol was prepared by mixing together the followingingredients: Parts Geon 121 1 100 Paraplex G-62 2 50 Paraplex G-25 3 50Dibasic lead phosphite 5 Petromix #9 4 0.2 N,N-dinitroso, N,N-dimethylterephthalamide 7 Primol-D" 5 3 Dispersion-grade polyvinyl chloridemanufactured by the B. 1 Goodrich Chemical Co.

An epoxy polyester (average mol. wt. approx. 1000, specific gravity (25C. /15 C.) 0.993, freezing point 05 0.), manufactured by Rohm & Haas Co.

1 A polysebacate (average mol. wt. 8000, specific gravity (25 C./15 C.)0.993, freezing point 05 C.) manufactured by Rohm 8: Haas Co.

A polysebacate (average mol. wt. 8000, specific gravity (25 C:/15 C.)1.06, viscosity (100%, 25 C.) 1700 poises, refractive index (Nn25)1.470, freezing point 13-15 C.).

-An oil-base composition containing petroleum sulfonates fsortifietdwith auxiliary soaps, manufactured by L. Sonneborn ons, nc.

5A white paraifinic hydrocarbon oil, manufactured by Esso Standard OilCompany.

The plastisol was poured into an aluminum pan 20 inches square, 2 inchesdeep, and having a wall thickness of inch. The plastisol was poured intothe pan to a depth of inch, then heated for 1% hours in acirculating-air oven having an air temperature of 177 C. It was notedthat the blowing agent had completely decomposed and foaming wascomplete within minutes after the plastisol was placed in the oven.Temperature measurements in the plastisol indicated that foaming beganat 60 C. and was complete at 125 C.

The product was a white sponge, free from objectionable odor. It had afine, open cell structure, a density of 7 lbs. per cubic inch, and avolume 11.5 times that of the original plastisol.

The above examples illustrate the application of our novel process tothe preparation of cellular compositions having an open or continuouscell structure.

We have also found that the addition of the additives described abovemakes possible the preparation at atmospheric pressure of cellularpolyvinyl chloride having a very high proportion of closed cells, whichare very fine in size and not very easily ruptured in usage. The priorart suggests the preparation of sponge having a high proportion ofclosed cells in the same formulations using substantial amounts of fattyacid soaps, such as calcium stearate, but thegclosed cells so obtainedare coarse and 8 relatively easily ruptured. The advantages, oftheadditives of our invention in this connection are illustrated by thefollowing examples: V Example 18 p A plastisol was prepared by mixingtogether the follow ing ingredients: Parts Bakelite QYNV 1 10o ParaplexG53 2 50 Paraplex G-62 3 50 Dibasic lead phosphite 5 Barium petroleumsulfonate 4 -l. 3.6 N,N-dinitroso, N,N-dimethyl terephthalamide 7,Primol-D 5 3 Dispersion-grade polyvinyl chloride, manufactured by theBakelite Co.

A polyadipate (specific ravity (25 C./15 C.) 1.1015,

freezing point approx. 10 manufactured by Rohm and Haas Co.

a An epoxy polyester (average mol. specific gravity (25 C./15 C.) 0.993,freezing point 05 manufactured by Rohm and Haas Co.

A mixture of barium di-o-dodecyl benzene monosulfonate and bariumdip-dodecyl benzene monosulfonate (30% active ingredient having mol. wt.9 A.S.T.M. base No. 0.5), manufactured by Bryton Chemical Co.

A white parafiinic hydrocarbon oil, manufactured by Esso Standard OilCompany.

The plastisol was treated in exactly the same manner as that ofExample 1. The product was a white sponge, having no objectionable odor.It had a fine, uniform cell structure, a density of 8.6 lbs. per cubicfoot, and a volume 10 times that of the original plastisol. This spongecontained a high proportion of closed cells as shown by the followingtest: The sponge was submerged in a pan of water within a bell jar. Thejar was evacuated. The sponge swelled toseveral times its originalvolume. The system was then allowed to return to atmospheric pressureand the sponge returned to its original dimensions. Further examinationof the sponge showed that it had absorbed only about 15% of its weightof water. A sponge known to have an open cell structure absorbed over500% of its weight of water when put through a similar procedure.

Example 19 The procedure of Example 18 was repeated except that thebarium petroleum sulfonate was obitted from the plastisol. The productwas a white sponge, free from objectionable odor. It had a medium-fine,open cell structure, a density of 7.5 lbs. per cubic foot, and a volume11.5 times that of the original plastisol. This sponge was submitted tothe water immersion test described in Example 18. It did not expand onevacuation of the bell jar, and it was found to have absorbed over 500%of its weight of water in the fashion of the sponge known to be of theopen cell variety.

Example 20 A plastisol was prepared by mixing together the followwt.approx. 1000, C.

ing ingredients: Parts Exon 654 Paraplex G-60 2 44 Ohopex Q-lO 3 40Methyl pentachlorostearate 40 Dibasic lead phosphite 5 Barium petroleumsulfonate 3.6 N,N-dinitroso, N,N'-dimethyl terephthalamide 7 Primol-D 53 Dispersion-grade polyvinyl chloride, manufactured by FirestonePlastics Co.

An epoxy polyester (average mol. wt. 1000, specific gravity (25 C./15C.) 0.990, viscosity (100%, 25 0.) 2-3 poises, refractive index (Nn25)1.472, freezing point 0 5 C.), manufactured by Rohm 8: Haas Co. inaccordance with U.S. Patent No. 2,485,160, issued October 18, 1949.

Octyl fatty-phthalic acid esters, manufactured by Ohio- Apex Inc.

*A mixture of barium di-o-dodecyl benzene monosulfonate and bariumdi-p-dodecyl benzene monosulfonate (30% active ingredient having mol.wt. 991 A.S.T.M. base No. 05), manufactured by Bryton Chemical Co.

A white parafiinic hydrocarbon oil, manufactured by Esso Standard OilCompany.

The plastisol was treated in exactly the same manner as that ofExample 1. The product was a white sponge, free from objectionable odor.It had a very fine cell structure, a density of 10.6 lbs. per cubic footand a volume 8 /3 times that of the original plastisol. This sponge waspredominantly closed-cell as indicated by its behavior on beingsubjected to the water immersion test described in Example 18.

From the foregoing examples it is evident that additives of the typedisclosed are elfective with a wide variety of plasticizers. Thus, forinstance, several of the above examples illustrate the use ofmonomeric-type plasticizers. Several others illustrate the use ofpolyester-type plasticizers, while still others employ a mixture of thetwo types. Regardless of the type of plasticizer used, the addition ofan additive of the type disclosed greatly enhances the product.

Though the invention is applicable to the preparation of expandedcellular polyvinyl chloride compositions with any of a variety ofblowing agents, the addition of these additives to the plastisol beforeblowing is particularly effective when the blowing agent employed isN,N-dini troso, N,N-dimethyl terephthalamide and kindred compounds suchas N,N'-dinitroso, N,N'-dimethyl isophthalamide and N,N-dinitroso,N,N'-diethyl terephthalamide. A preferred process for the preparation ofthese compounds may be found in the pending U.S. patent applicationSerial No. 316,076, filed October 21, 1952, now U.S. Patent No.2,754,326, issued July 10, 1956, and having a common assignee with theinstant application.

The additive of the present invention may be used in amounts of about0.5%, as in Example 15, to about 1.5%, as in Example 13, based on theweight of the resin. Good results have been obtained with about 1% ofthe additive based on the weight of the resin, as illustrated inExamples 2, 3, 7 through 12, 16, 18, and 20, and this represents thepreferred operating proportion.

Having thus described and illustrated our invention, We intend to belimited only by the following claims:

1. A process for the preparation of an expanded cellular compositionwhich includes the essential steps of forming a plastisol by mixingsuitable portions of a dispersion-grade polyvinyl chloride, aplasticizer, from about 0.5% to about 1.5%, based on the weight of thepolyvinyl chloride, of an additive selected from the class consisting ofthe hydrocarbon oil-soluble alkali metal and alkaline earth metal saltsof alkaryl sulfonic acids, and N,N'-dinitroso, N,N'-dirnethylterephthalamide as a chemical blowing agent, heating said plastisol toabout the temperature of decomposition of the blowing agent, and

thereafter heating said plastisol to a higher temperature to accomplishthe gelation of the plastisol after the blowing agent has decomposed andfoamed same.

2. The process of claim 1 wherein the additive is a hydrocarbonoil-soluble alkaline earth metal salt of an alkaryl sulfonic acid.

3. The process of claim 1 wherein the additive comprises a mixture ofthe alkaline earth metal salts of dio-dodecyl benzene sulfonic acid anddi-p-dodecyl benzene mono-sulfonic acid.

4. The process of claim 2 wherein the alkaline earth metal salt is abarium salt of an alkairyl sulfonic acid.

5. The process of claim 2 wherein the alkaline earth metal salt is acalcium salt of an alkaryl sulfonic acid.

6. A plastisol composition for use in the preparation of expandedcellular compositions comprising a mixture of a dispersion-gradepolyvinyl chloride, a plasticizer, from about 0.5% to about 1.5%, basedon the weight of the polyvinyl chloride, of an additive selected fromthe class consisting of the hydrocarbon oil-soluble alkali metal andalkaline earth metal salts of alkaryl sulfonic acids, andN,N'-dinitroso, N,N'-dimethyl terephthalamide as a chemical blowingagent.

7. A plastisol composition for use in the preparation of expandedcellular compositions comprising a mixture of a dispersion-gradepolyvinyl chloride, a plasticizer, from about 0.5 to about 1.5 based onthe weight of the polyvinyl chloride, of a hydrocarbon oil-solublealkali metal salt of an alkaryl sulfonic acid, and N,N- dinitroso,N,N'-dimethyl terephthalamide as a chemical blowing agent.

8. A plastisol composition for use in the preparation of expandedcellular compositions comprising a mixture of a dispersion-gradepolyvinyl chloride, a plasticizer, from about 0.5 to about 1.5 based onthe weight of the polyvinyl chloride, of a hydrocarbon oil-solublealkaline earth metal salt of an alkaryl sulfonic acid, and N,N'-dinitroso, N,N'-dimethyl terephthalamide as a chemical blowing agent.

References Cited in the file of this patent UNITED STATES PATENTS2,433,849 Lathrop et a1 Jan. 6, 1948 2,466,826 Romaine Apr. 12, 19492,525,966 Smith et =21 Oct. 17, 1950 2,609,347 Wilson Sept. 2, 19522,676,928 Frank Apr. 27, 1954 2,732,353 Fuller n Jan. 24, 1956 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noo 2,904,522September 15, 1959 Willard E, Catlin et It is hereby certified thaterror appears in the printed specification of the above numbered patentrequiring correction and that the said Letters Patent should readascorrected below.

Column 2 line 34, following "Bryton Chemical O00" insert a closingparenthesis; column 5, line 64, for "d.i==o==decyl" read. cli oclocieoyl column 6, line 19, for AP. 'epom" reed M An epoxy column '7lines 42 and 43, strike out the entire 3-lino footnote column 8, linefor obitted" read omitted =0 Signed and sealed. this 29th day of March1960.,

SEAL) Attest:

KARL Ho AJGLINE ROBERT C. WATSON Attesting Officer Commissioner ofPatents

1. A PROCESS FOR THE PREPARATION OF AN EXPANDED CELLULAR COMPOSITIONWHICH INCLUDES THE ESSENTIAL STEPS OF FORMING A PLASTISOL BY MIXINGSUITABLE PORTIONS OF A DISPERISON-GRADE POLYVINYL CHLORIDE, APLASTICIZER, FROM ABOUT 0.5% TO ABOUT 1.5%, BASED ON THE WEIGHT OF THEPOLYVINYL CHLORIDE, OF AN ADDITIVE SELECTED FROM THE CLASS CONSISTING OFTHE HYDROCARBON OIL-SOLUBLE ALKALI METAL AND ALKALINE EARTH METAL SALTSOF ALKARYL SULFONIC ACIDS, AND N,N''-DINITROSO, N,N''-DIMETHYLTEREPHTHALAMIDE AS A CHEMICAL BLOWING AGENT, HEATING SAID PLASTISOL TOABOUT THE TEMPERATURE OF DECOMPOSITION OF THE BLOWING AGENT, ANDTHEREAFTER HEATING SAID PLASTISOL TO A HIGHER TEMPERATURE TO ACCOMPLISHTHE GELATION OF THE PLASTISOL AFTER THE BLOWING AGENT HAS DECOMPOSED ANDFOAMED SAME.